12221( 3) - 26-Jul-2010 13:34:00 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12221 Version: 3 Check-in Time: 26-Jul-2010 13:34:00 STScI Edit Number: 1 Title The role of photoevaporation in clearing protoplanetary disks: mapping flows and determining mass flow rates ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ilaria Pascucci Space Telescope Science Institute CoI: Dr. Suzan Edwards Smith College N CoI: Dr. Uma Gorti SETI Institute N CoI: Dr. David J. Hollenbach SETI Institute N ------------------------------------------------------------------------------------ Abstract The lifetime of an isolated protoplanetary disk is thought to be set by the combination of viscous accretion and photoevaporation driven by high-energy photons from the central star. While diagnostics of accretion are numerous and mass accretion rates are routinely measured, diagnostics of centrally driven disk photoevaporation are just emerging. The [OI] 6300 angstrom is expected to trace slow disk winds extending out to 30-40 AU from the central star if driven by stellar Xrays. We propose to use this line diagnostic to measure for the first time the radial extent of the photoevaporative flow and the disk photoevaporation rate. Our targets are two nearby T Tauri disks with dust depleted inner regions, low stellar accretion rates, and ancillary evidence for on-going photoevaporation. Slitless spectroscopy with STIS will enable us to map these flows at a spatial resolution of ~6 AU. From their extension we will determine whether stellar EUV or Xrays drive most of the photoevaporation, provide the first measurements of mass flow rates, and thus constrain expected disk lifetimes. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will perform slitless spectroscopy of two nearb protoplanetary disks around TW Hya and T Cha using the G750M/6252 setting with STIS. Our goal is to spatially resolve the [OI] 6300AA emission from these disks and thus constrain disk photoevaporation models. The [OI] 6300AA line is the brightest emission line in the 5966?6538AA wavelength range covered by the G750M/6252 setting, followed by the [OI] 6364AA (about a factor of 2 weaker). The two lines will be well separated and kinematically unresolved from both targets, which will make it easier to interpret the emission line images. We do not expect to spatially resolve any other emission line from these two disks. For target acquisition we will use the recommended longpass F28X50LP filter and 1sec exposure. For each target we will have two position angles (as much as possible perpendicular to each other) to accurately remove the stellar spectrum. Real Time Justification 12221( 3) - 26-Jul-2010 13:34:00 - [ 2] ----------------------- 1 orbit per target times 2 position angles per target times 2 targets = 4 orbits. We estimated that in 1 orbit (about 40min on-source exposure) we will reach a S/N of over 100 per resolution element. Calibration Justification ------------------------- We do not require any special calibration Additional Comments ------------------- ------------------------------------------------------------------------------------ 12221( 3) - 26-Jul-2010 13:34:00 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 V-TW-HYA STAR, T TAURI STAR RA=11H01M51.9063S +/- 0.2", J2000 V = 11.07 DEC=-34D42'17.02" +/- 0.2" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Coordinates are from Hipparcos ------------------------------------------------------------------------------------------------------------------------------------ 2 V-T-CHA STAR, T TAURI STAR RA=11H57M13.5305S +/- 0.2", J2000 V = 11.86 DEC=-79D21'31.54" +/- 0.2" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Coordinates are from Hipparcos ------------------------------------------------------------------------------------------------------------------------------------ 12221( 3) - 26-Jul-2010 13:34:00 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.2789 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 90.0 Angle_Between_Sides Center_Pattern NO Pattern_Comments: The point spacing is 5.5pixels*0.0507arcsec. This is chosen to improve the spatial resolution ------------------------------------------------------------------------------------------------------------------------------------ 12221( 3) - 26-Jul-2010 13:34:00 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-TW-HYA STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S ------------------------------------------------------------------------------------------------------------------------------------ 2 V-TW-HYA STIS/CCD ACCUM 50CCD G750M 6252 1 1000. S PATTERN 1 2 see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-TW-HYA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 1 1 555.0 S V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 2 1 555.0 S V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 1 1 555.0 S V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 2 1 555.0 S 12221( 3) - 26-Jul-2010 13:34:00 - [ 6] Visit: 02 Visit Requirements: ORIENT 90D TO 90D FROM 01; AFTER 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-TW-HYA STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S ------------------------------------------------------------------------------------------------------------------------------------ 2 V-TW-HYA STIS/CCD ACCUM 50CCD G750M 6252 1 1000. S PATTERN 1 2 see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-TW-HYA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 1 1 555.0 S V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 2 1 555.0 S V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 1 1 555.0 S V-TW-HYA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 2 1 555.0 S 12221( 3) - 26-Jul-2010 13:34:00 - [ 7] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-T-CHA STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S Comments: Note: T Cha is higly variable in V: literature values are from 11.2 to 12.7 in Vmag ------------------------------------------------------------------------------------------------------------------------------------ 2 V-T-CHA STIS/CCD ACCUM 50CCD G750M 6252 1 1000. S PATTERN 1 2 see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-T-CHA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 1 1 644.0 S V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 2 1 644.0 S V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 1 1 644.0 S V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 2 1 644.0 S 12221( 3) - 26-Jul-2010 13:34:00 - [ 8] Visit: 04 Visit Requirements: ORIENT 90D TO 90D FROM 03; AFTER 03 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-T-CHA STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S ------------------------------------------------------------------------------------------------------------------------------------ 2 V-T-CHA STIS/CCD ACCUM 50CCD G750M 6252 1 1000. S PATTERN 1 2 see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-T-CHA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 1 1 644.0 S V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 1 none none 2 1 644.0 S V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 1 1 644.0 S V-T-CHA 2 STIS/CCD ACCUM 50CCD G750M 6252 2 none none 2 1 644.0 S 12221( 3) - 26-Jul-2010 13:34:00 - [ 9] Summary Form for Proposal 12221 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 50CCD, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01, AFTER 03, ORIENT 90D TO 90D FROM 01, ORIENT 90D TO 90D FROM 03, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G750M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names V-T-CHA, V-TW-HYA ------------------------------------------------------------------------------------------------------------------------------------